readline

char *readline(FILE *in) {
    #define MAX_SIZE    512

    int size = MAX_SIZE;
    char *str = malloc(sizeof(char) * size);
    char *pos;

    while(fgets(str + size - MAX_SIZE, MAX_SIZE, in)) {

        if(pos = strchr(str + size - MAX_SIZE, '\n')) {
            *pos = '\0';
            break;
        }

        size = size + MAX_SIZE - 1;
        str = realloc(str, sizeof(char) * size);
    }

    return str;
}